BostonGlobe.com Political Headlines - September 20, 2012

Here are the top POLITICAL headlines from BostonGlobe.com today: 

• Romney's words hinder his campaign: Mitt Romney's campaign problems cannot be fixed with staff changes, since it is the candidate's own words that are being used against him. Globe politics reporter Matt Viser writes.

• Scott Brown, Elizabeth Warren face unique challenges in first debate: Senator Scott Brown and Elizabeth Warren face delicate challenges: She must engage him on issues without seeming aggressive; he must fend her off without hurting his likable image. State House bureau chief Frank Phillips reports.

• Partisan messages now easier than ever to spread with film, video: It is easier than ever to get a message, innocuous or incendiary, in front of the world's eyeballs, whether through movie theaters or by taking one's case to YouTube. Globe film critic Ty Burr explains. 

• Why do Mass. politicians wither on national stage: What is it about Massachusetts politicians who run for president? Is it something in the local air, or maybe in the ivory towers that nurtured them? Globe columnist Joan Vennochi ponders.

• Democrats face tough odds to regain House control: The contests in New Hampshire serve as microcosms of the battle for control of the US House, as Democrats hit Republicans over Medicare and the so-called Ryan budget. Globe politics reporter Bobby Caina Calvan writes.

• Romney-Ryan Medicare plan dependent on effective competition : The success or failure of the Republican plan depends largely on the answer to one key question: Would competition among private insurers hold down insurance costs? Globe correspondent Callum Borchers explains.

New poll shows Scott Brown leading Elizabeth Warren, after four other polls showed Warren ahead: Warren's DNC momentum fades as tight Senate race swings again. Globe politics reporter Noah Bierman details.